The compounds of this invention are novel benzothiazoline derivatives wherein the substituent at 3-position on the benzothiazoline ring is lower alkanoyl and that at 2-position is phenyl which is resubstituted by ether group at any position. 2-Phenylbenzothiazoline derivatives were reported by H. Breuer et al. (U.S. Pat. No. 3,720,683), H. D. Cossey et al. (J. Chem. Soc., 1965, 954) and P. J. Palmer et al. (J. Med. Chem., 14, 248). The U.S. Pat. of Breuer et al. relates to 2-phenylbenzothiazoline derivatives in which phenyl nucleus is substituted by alkyl, etc. but not ether group, and the pharmacological effects are for anti-inflammatory and anti-microbial. Cossey et al. and Palmer et al. reported 2-phenylbenzothiazoline derivatives in which phenyl nucleus is substituted by ether group, but the substituent of 3-position is not lower alkanoyl but hydrogen, alkyl, benzyl, etc., and the pharmacological effect is for anti-microbial.